© 2019 Fraunhofer IWES 1© 2019 Fraunhofer IWES 1© 2020 Fraunhofer IWES 1
Torben Jersch
Future challenges for grid integration testing
and needs for standardization of testing
29.04.2020
2© 2019 Fraunhofer IWES 2© 2019 Fraunhofer IWES 2© 2020 Fraunhofer IWES
Who are we
Grid Integration testing actual developments
Testing at test benches
Actual model requirements according to 61400-27
HVDC blocking
EMT-Models
Outline
Agenda
3© 2019 Fraunhofer IWES 3© 2019 Fraunhofer IWES 3© 2020 Fraunhofer IWES
Department System Validation Mechanical Drive Train
Department System Technology
33 employees + students
Mechanical integration and cooling
Non-torque load application
Control of 10 MW prime mover and inertia-control
MV system and grid emulation
Automation system and data handling
Mechanical, electrical measurement and data handling
Numerous research Projects
Grid Integration Testing at DyNaLabWho
Certification ofelectrical properties
Nacelle testing
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Electrical models are required for grid integrations studies
Validation of grid code requirements
Why do we need standardized validation processes
Standard models for embedding them in various simulation tools
Standardized validation process for assuring high quality measures
Unified process will reduce overall costs
Interest of Industries in Grid Integration Testing
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WEC System tests in the field
Functional tests of components
Necessary improvements
Reproducibility of test results
Accelerated testing and certification
process
Cost reduction
Grid Integration of Wind Turbines2011-2013 IWES starts thinking about development of novel test methodologies on test
benches
Actual Design and Validation ProcessIdeal Design and Validation Process
Inverter Testing
Subsystem Testing
System Testing
Field Testing
Field System Testing
SW -Hil Testing
Inverter & Components
Electrical Drivetrain
Electrical System (Nacelle)
WEC
Wind Farm
Controller & PLC
Product Requirements
Validated Product Product
RequirementsValidated Product
Engineering Testing
N.A.
N.A.
Field Testing
Model Aggregation
Hil*
Inverter & Components
Minimal-Sys.
Electrical System (Nacelle)
Wind Turbine
Wind farm
Controller & PLC
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Use of nowadays validation and certification process
Objective: Obtaining equivalent results on test benches compared to field tests
Electrical system testing on test benches – (IWES concept/spec./development 2013-2015)
Grid Compliant Testing on DyNaLab
LSS M1Gbx.
HSS
Gen.
AC
DC
DC
AC
Aux.
Nacelle
TurbineControlSystem
Switch gear
Conv.
TestbenchHIL
control
Wind, P, Q, Pitch
Torque
M2Trafo
Filter
Feed-forward controlled Voltage 50 HZ impedance control
MV-Grid EmulationEmulation of WEC
wind rotor dynamicEmulation of voltage
behavior
Emulation of realistic field conditions
Focus on FRT testing by design of 44 MVA grid emulator
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DyNaLab Test Bench: Nacelle and drive train TestingCommissioned 2015
Developing test benches Together with test
methodology
ACS 6000 3,3kV IGCT-Inverter
2x Drive 5MW @11rpm
Junction-Box(Disconnect/Grounding
& Measurement)
SpecimenIWES DyNaLab(existing)
3x4~
2=2x3~
2=
44MVA18MVA
2x3~
2=
2x3~
2=
13 MVA 13 MVA
9MVATransformer
15 MVATransformer
ESM ESM
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Objective: Obtaining equivalent results on test to that of the DyNaLab nacelle test bench
Reduction of through-put times on the test bench
HiL-Grid-CoP – Testing of reduced systems / (relevant WEC E-Systems) - 2016/2017
Grid Compliant Testing on HiL-Grid-CoP
Emulation of wind rotor and drive train
dynamics
Emulation of voltagebehavior
Accelerate the certification process
Creation of broad acceptance for test procedures on test benches
HSS
Gen.
AC
DC
DC
AC
Minimal System
TurbineControlSystem
Conv.
TestbenchHIL
control
Wind, P, Q, Pitch
Torque
Trafo
Filter
M1
Feed-forward controlled Voltage 50 HZ impedance control
MV-Grid Emulation
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Advantages of the IEC61400-27
High simulation speed
Fully documented model
Visible open and modular model structure
Verified model structures
High model accuracy
Model user can use the models independently
Limits of the IEC61400-27
Usable bandwidth is recommended to 15 Hz
Range of model validity down to SCR of 3
Advantages / Limits of IEC 61400-27 modelsWEC Models for grid studies
• Increasing usage of renewable energy
• Changing grids to inverter dominated grids
• Classical modelling approaches won’t be valid
10© 2019 Fraunhofer IWES 10© 2019 Fraunhofer IWES 10© 2020 Fraunhofer IWES
Future Grid Integration Requirements – ToDo’sUnsolved challenges due to HPoPEIPS (High Penetration of Power Electric Interfaced Power Sources)
Wind turbines 15 MW +
Windfarm
GridformingControl
Further Cost Reduction
Time-to-Market
RoCoF
EMT-Model requirements
Black-Start
Impedance requirements
Weak-Grid-Conditions
Grid-WEAResonance
Harmonics
Low Total system
intertia
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Specific Application of HPoPEIPSNormal Operation of Offshore Wind Farm
Trafo
Conv.
Conv.
Trafo
OWP1
OWP2
Substation
HVDC-Station
33kV
33kV
155kV
155kV
220kV
380kV
DC
AC
DC
AC
SCR 1.1-2.2of holistic wind farm
Possibilities for controller interaction in HPoPEIPS Grids
Different legal entities
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Trafo
Trafo
OWP1
OWP2
Substation
HVDC-Station
33kV
33kV
155kV
155kV
220kV380kV
DC
AC
Current Source
Current Source
Current Source
Current Source
Voltage Source
Conv.
Conv.
Specific Application of HPoPEIPSElectrical surrogate model in normal operation
WEC acting as current source
HVDC acting as voltage source
Principle stable operation due to voltage
generation of HVDC
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Specific Application of HPoPEIPSElectrical surrogate model in HVDC blocking condition
Trafo
Trafo
OWP1
OWP2
Substation
HVDC-Station
33kV
33kV
155kV
155kV
220kV380kV
DC
AC
Current Source
Current Source
Current Source
Current Source
Rectifier
Conv.
Conv.
HVDC acting as Rectifier source
Not stabilized operation
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Measurement of HVDC BlockingCrucial subsequent faults due to HVDC blocking
Source: Erlich, I., et al. "Overvoltage phenomena in offshore
wind farms following blocking of the HVDC converter." 2016
IEEE Power and Energy Society General Meeting (PESGM). IEEE, 2016.
300 ms300 ms
130% Overvoltage
Transformer Saturation
Excitation of System resonances
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Modelling challenges:
High system dynamics
Non-linearity e.g. saturation of transformer
Dynamic change of the impedance
No Standards for EMT modelling of WEC or OWP
No Standards for EMT-Model Validation
No Standards for future Control Concepts (e.g. Grid-Forming)
No Standards for dealing with large HPoPEIPS-Grids
EMT-Modelvalidation Why actual models and validation processes are not sufficient
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Back2Back inverter testing
8 MVA specimen @ 690 V
High switching inverters - 100 kHz accumulated
Dynamic control of grid impedance (2.5 kHz) for emulation of complex grid behavior
Harmonic injection up to 10 kHz
PQ4Wind Test Bench Focusing EMT-Model and impedance validation also for higher harmonics
AC
DC
DC
AC
Converter System
ConverterController
LV-HF-Grid Emulation
Conv.
WEA-HIL-ControlGenarator Impedance
Filter*
Grid-Impedance & el. Windfarm emulation
LV-HF-Generator Emulation
8 MW 8 MW
4 MW
Available in 2023
17© 2019 Fraunhofer IWES 17© 2019 Fraunhofer IWES 17© 2020 Fraunhofer IWES
Mobile-Grid-CopCertifying large Grid Forming Power Generation Units up to 20 MW
Key points
28 MVA Continuous Power/ 50 MVA (10
Minutes)
20kV/33 kV/66 KV | 1,5 x U_n
45-65 HZ
Harmonic Injection
Impedance Emulation >> Grid Emulation of
High Penetration of Power Electric Interfaced
Power Sources
~=
~=
=~
=~
=~
=~
~=
~=
=~
=~
=~
=~
DC Bus DC Bus
10 kV20 kV30 kV
ORGrid
PCC
Direct Link
Input
Tran
sfor
mer
Conve
rter
Outp
ut
Tran
sform
er
20 kV33 kV66 kV
Coolin
g
Coolin
g
Filter
SG
DUT
SG SG
Auxi
liary
Supply
Available in 2022
18© 2019 Fraunhofer IWES 18© 2019 Fraunhofer IWES 18© 2020 Fraunhofer IWES
Real-time Simulator for Offshore Energy Systems EMT-Model simulation for large Power Systems with 1 us Sample Time
Trafo
Conv.
Conv.
Trafo
OWP1
OWP2
Substation
HVDC-Station
33kV
33kV
155kV
155kV
220kV
380kV
DC
AC
DC
AC
1 GW Total Power
19© 2019 Fraunhofer IWES 19© 2019 Fraunhofer IWES 19© 2020 Fraunhofer IWES
We cooperate with the best players from industry and research in order to tackle challenges concerted and focused.
This approach allows us to handle research projects of any complexity. And to improve our methodological competence further in a systematic manner.
Facing future challenges together
20© 2019 Fraunhofer IWES 20© 2019 Fraunhofer IWES 20© 2020 Fraunhofer IWES
Thanks a lot for your attention!
21© 2019 Fraunhofer IWES 21© 2019 Fraunhofer IWES 21© 2020 Fraunhofer IWES
Federal Republic of Germany
Federal Ministry for Economic Affairs and Energy
Federal Ministry of Education and Research
European Regional Development Fund (ERDF):
Federal State of Bremen
Senator of Civil Engineering, Environment and TransportationSenator of Economy, Labor and PortsSenator of Science, Health and Consumer ProtectionBremerhavener Gesellschaft für Investitionsförderung und Stadtentwicklung mbH
Federal State of Lower Saxony
Free and Hanseatic City of Hamburg
AcknowledgementsFraunhofer IWES is funded by: